Sorry to hear about your big little guy. :-( It is so easy to get attached to them so quick!

I am not sure if you handeled him a lot or not after you got him, but I have found that the transition is a lot more comfortable for the frog (in my experience) if you refrain from holding them till they have adjusted. The thing is you never know what they went through to get to you! When I recieved my Whites I put them in their enclosure and refrained from touching or holding them for about 3 weeks. The reason I did this was they both came in brown. Although I know some Whites are brown in color naturally it is also a color of stress! So I let them adjust to make sure that they were in fact brown. After 3 week I had one that was a nice olive color and the other was a nice light blue! Just better to be safe then sorry. 3 weeks may have been excessive but it is a short time in my opinion to ensure their health.

This was the one thing that came to mind! I may be way off base as I have only had experience with 3 Whites, which one I lost immediatly that I blame myself for possibly over doing it with contact when I first got him!